1. Field of the Invention
The present invention refers to a new lining for driving or striking caps. These caps are used in conjunction with pile-drivers, which are operated by a gaseous medium under pressure.
2. Discussion of the Prior Art
Pile-drivers employed for driving in objects, e.g., stakes, consist of a cylinder, a piston situated inside the cylinder and a ram block, which can be moved backwards and forwards by the piston, and is thereby driven against a driving or striking cap. This cap transfers the powerful impact to the object which is to be driven in, e.g., a stake or a girder. A control valve, situated on or near the cylinder, regulates the flow of the pressure medium to the cylinder in order that the piston and the ram block can be moved up and down. A control column, connected to the ram block, moves up and down in conjunction with it thereby effecting the required movements of the control valve. The impact of the driving or striking cap, which transfer the energy of the ram block to the object which is to be driven in, gives rise to serious noise disturbance and, in addition, this impact can have a destructive effect on the pile-driver itself as well as on the object to be driven in.
It is therefore customary to provide the driving or striking caps, which lie between the ram block and the object to be driven in, with an impact transmitting lining. Possible materials for this purpose are, e.g., hard wood, asbestos, polyamide or fiber-reinforced phenol-melamine resin moulding compounds. The known driving or striking cap linings do not meet all the demands made of them. This is especially true with regard to their abrasion resistance, impact strength and, in many cases, their ease of handling. Due to the high energy transfer, the hard wood linings often become sintered to the cap and have to be chiselled out. Asbestos and fibers reinforced with phenolic resins have only a minor impact strength.